                A first airtight compartment containing a heat-delivering substance to heat the liquid in the device;        A second airtight compartment containing a measured amount of liquid to be heated;        A third airtight compartment containing a measured amount of dry matter for preparing a hot drink:        A filter for separating the dry matter from the liquid (optional);        A fourth compartment containing a measured amount of liquid to actuate the heat-delivering substance.        
Methods for preparing an individual quantity of hot drink are commonly known and generally include, in the most elementary form, a heat source which, when actuated, warms up a cold, premixed beverage. Such a device has the advantage that with a limited number of actions and at a low price, a warm drink can be prepared, e.g. premix coffee. Such a device has the disadvantage that organoleptic properties of the prepared drink are relatively poor.
The organoleptic properties can be improved by mixing with a warm liquid. WO 93/15641 describes a self-heating can with a heat source and a reservoir with a fluid to be heated. which is linked to a space containing a concentrate and a cup to receive the warm drink. Such a device includes as the elements to quickly prepare a hot drink with reasonable organoleptic properties. but has the disadvantage that the steam from the heating element creates a pressure difference inside the device, making it complex and expensive.
A further improvement of the organoleptic properties can be achieved through extraction of smell and flavours from a fine, powdered, dry substance, such as ground coffee, using a heated liquid. U.S. Pat. No. 6,298,771, for example, describes a device and method for making coffee from ground coffee beans placed in a filter through which a heated liquid is percolated under the influence of gravity.
The advantage of this device is that the ground coffee has a relatively long shelf life, and that a fresh cup of coffee can be made quickly. The disadvantage of such a device is that the process is laborious because the hot liquid should be added separately and therefore an external heat source is needed.
In addition to the organoleptic properties, ease of use is an important aspect for a device to prepare such a hot drink. The number of actions for a user to prepare such a warm drink must be minimal and should be in accordance with a unique instruction. presented on the package. A single location, e.g. a button, for actuation and a single orientation of the device with respect to a subsurface is preferable to multiple buttons actuation and orientations to a subsurface.
The heat source is preferably actuated at the top of the device and not at the bottom, such as known from EP 1213227, which describes a can for beverages which is equipped with an opening at the bottom, where a metal heating element is located. After actuation of the heating element the device has to be turned over before opening it at the top, for consumption. Such a device has the additional disadvantage that the user can make direct contact with the hot heating element and that the price is relatively high.